Projectors typically use a hold-type display element such as a liquid crystal panel as a light modulation element that modulates light according to an image signal. Such a hold-type display element produces so-called sample-and-hold blur (motion blur). The sample-and-hold blur is generated by the following reason. When a viewer observes a moving image displaying a moving object, he/she moves his/her direction of eyes to a direction to which the moving object is predicted to move. On the other hand, the hold-type display element holds displaying a same frame image within one frame period ( 1/60 second). Thus, the viewer recognizes a difference between a position followed by his/her eyes and a position of the moving object displayed in the moving image as an image blur (sample-and-hold blur).
As a method for reducing such sample-and-hold blur, Patent Document 1 discloses a method of dividing a liquid crystal panel (displaying screen) of a liquid crystal display apparatus into multiple regions in a vertical scanning direction and sequentially turning on and off a backlight for each of the multiple regions so as to restrict an image display time to be near a time of image writing to the liquid crystal panel. This method is well known as a black frame insertion method. Patent Document 2 discloses a method of forming, in a projector, a narrow region where a display element is illuminated with illumination light in a vertical scanning direction and scanning the display element with the illumination light via a rotational prism in the vertical scanning direction so as to reduce the sample-and-hold blur.